Canton 3.4 to 3.5 Upgrade Plan
Summary
On Canton Network we outline the transition from Canton 3.4 to 3.5 covering Phase 1 Splice 0.5.x pause and MainNet Daml model changes, Phase 2 Splice 0.6.x rollout with Logical Synchronizers and validator upgrade guidance, and Phase 3 Global Synchronizer network upgrades. Key dates include May 5 MainNet Daml go-live and April 27 DevNet 0.6.1.
CANTON 3.4 TO CANTON 3.5 TRANSITION
Update: 2026-04-24
See details in the long-term SV Operations schedule
Phase 1: Splice 0.5.x releases pause, and multiple new Splice Daml models go into effect
- The Splice 0.5.x release line is complete
Daml Models and configuration settings going live on MainNet in Phase 1:
- Development Fund Manager Party is now live on MainNet as of April 15th.
- CIP-0104 Traffic-based App Rewards Increments 2 and 3 are in effect on MainNet
- May 5th: Daml models from Splice 0.5.16 go live on MainNet. All Validators must upgrade to Splice 0.5.16 on MainNet before this date.
Phase 2: Splice 0.6.x Release line. Splice 0.6.x begins to introduce features from Canton 3.5 as part of the standard bundle. Protocol-breaking changes remain behind feature flags.
- Splice 0.6.0 had errors in early testing by SVs on DevNet.
- Splice 0.6.1 will be released to SVs on Monday, April 27th.
- Validators should not upgrade until at least Tuesday, April 28th.
- Splice 0.6.x will introduce Logical Synchronizers, along with the ability to upgrade between two physical synchronizer nodes while preserving the same Logical SynchronizerID
- This will allow protocol-changing upgrades to take place without pausing Daml transactions. Topology transactions, like adding new nodes, onboarding parties, and vetting Daml models, do pause during protocol-changing upgrades.
Major Milestones for Splice 0.6.x:
- April 27th: Splice 0.6.1 goes live on DevNet. Logical Synchronizer introduced.
- April 30th: Validator Liveness Rewards reduced to zero (0).
- Late May:* Super Validators practice an upgrade using a Logical Synchronizer (aka Logical Synchronizer Upgrade / LSU) on DevNet. No actual protocol changes will be introduced in this practice.
Phase 3: Upgrade Global Synchronizer networks to Canton Protocol 35
- After proving out Logical Synchronizer upgrades on Splice 0.6.x, all three Global Synchronizer networks will perform a Logical Synchronizer upgrade to Canton protocol Version 35.
- Final timing and numbering of this upgrade, and the specific Canton 3.5 features to be included along with it, is still TBD. New features will roll out over time, relying on LSUs to minimize impact on Node Operators and App Providers.
Major Milestones for Phase 3:
- Early June: LSU on DevNet introduces protocol upgrade and major new features. TestNet LSU follows one week later.
- Mid-June: LSU on MainNet introduces protocol upgrade. New features introduced, following the same feature flags and upgrade procedures introduced on DevNet and TestNet.
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